The invention relates to a transponder communication device for the contactless communication with mobile transponders, comprising interrogation means for generating at least one type of interrogation information by means of which mobile transponders, which are in an active state and which are situated within a receiving range of the transponder communication device, can each be requested to generate and transmit answer information, and transmission means for transmitting interrogation information to a mobile transponder situated within the receiving range, and receiving means for receiving answer information generated and transmitted by mobile transponders within the receiving range in response to the interrogation information of at least one type, and answer information detection means with the aid of which the presence of a mobile transponder within the receiving range can be detected depending on the occurrence of answer information of at least one type.
The invention further relates to a transponder for the contactless communication with a transponder communication device, which transponder is capable, when in an active state, of communicating with a transponder communication device, the transponder including receiving means for receiving at least one type of interrogation information transmitted by means of a transponder communication device and interrogation information detection means for detecting received interrogation information of at least one type and answer means controllable by the interrogation information detection means to generate answer information in response to received interrogation information detected by the interrogation information detection means, and transmission means for transmitting the answer information generated by the answer means.
Such a transponder communication device of the type defined in the first paragraph and such a transponder of the type defined in the second paragraph are known, for example from the document U.S. Pat. No. 5,345,231 A. As has been stated in said document, the known transponder communication device and the known transponder can be parts of a transponder system, which may be a toll collection system, an access control system, a tool changing system and the like. Particularly in those transponder systems in which the transponder communication device or an apparatus including the transponder communication device is accessible to the public, as for example in the case of public telephones having an integrated transponder communication device, it is necessary to check or test the proper working order of a transponder communication device included in a such a transponder system. To date such a test is carried out in such a manner that a qualified person trained for this personally carries out an on-site inspection of the transponder communication device, which is laborious and expensive.